The continents preserve some of Venus's oldest terrain—the tesserae. These regions, which include Ovda Regio, have undergone a phenomenal amount of folding and faulting. They look like islands of an older surface that escaped the volcanic flooding that covered most of Venus.
Venus may have had a plate-tectonics cycle. Portions of both Aphrodite and Ishtar resemble the regions on Earth where plate tectonics have been active, building new crust and destroying the old.
Maxwell Montes, a rugged range in Ishtar, contains the highest point on Venus and stands more than 7 miles (11 km) above the global lava plain. It is much too massive to be supported as a single block of crust. Only plumes of molten rock rising from the mantle could sustain it.